Use these burs to cut a seat for faceted stones in bone dry clay. Cuts very easily by hand with a few turns, or put in a pin vise for a better grip. First drill a pilot hole for an azure (a light hole) and then cut the seat with the bur. Stone table should sit below the surface by a small amount so the clay shrinks around the girdle. Choose the bur that matches the stone size you wish to set. To set stones in fired metal, install bur in a flex shaft and lubricate with Cut Lube and slow speed. Top quality burs should be treated with care. Do not overheat with high speed.